Simplify hphp_unpack_continuation

Do not generate yield labels as normal goto labels in the parser. Create
them at YieldExpression and use m_yieldLabels array in emitter.

hphp/compiler/analysis/emitter.cpp

@@ -2294,12 +2294,6 @@ bool EmitterVisitor::visitImpl(ConstructPtr node) {
         bool enabled = RuntimeOption::EnableEmitSwitch;
         SimpleFunctionCallPtr
           call(dynamic_pointer_cast<SimpleFunctionCall>(subject));
-        bool isGenerator = call &&
-          call->isCompilerCallToFunction("hphp_unpack_continuation");
-        if (enabled && isGenerator) {
-          emitContinuationSwitch(e, sw);
-          return false;
-        }
 
         SwitchState state;
         bool didSwitch = false;
@@ -3151,10 +3145,11 @@ bool EmitterVisitor::visitImpl(ConstructPtr node) {
             }
           }
         } else if (call->isCompilerCallToFunction("hphp_unpack_continuation")) {
-          assert(params && params->getCount() == 1);
+          assert(!params || params->getCount() == 0);
+          int yieldLabelCount = call->getFunctionScope()->getYieldLabelCount();
           inputIsAnObject(0);
-          e.UnpackCont();
-          return true;
+          emitContinuationSwitch(e, yieldLabelCount);
+          return false;
         } else if (call->isCompilerCallToFunction("hphp_create_continuation")) {
           assert(params && (params->getCount() == 3 ||
                             params->getCount() == 4));
@@ -3839,10 +3834,7 @@ bool EmitterVisitor::visitImpl(ConstructPtr node) {
         e.ContExit();
 
         // emit return label
-        StringData* nName = StringData::GetStaticString(
-          YIELD_LABEL_PREFIX + boost::lexical_cast<std::string>(y->getLabel()));
-        Label& lab = m_gotoLabels[nName];
-        lab.set(e);
+        m_yieldLabels[y->getLabel()].set(e);
 
         // check for exception and retrieve result
         assert(m_evalStack.size() == 0);
@@ -4805,58 +4797,35 @@ void EmitterVisitor::emitClsIfSPropBase(Emitter& e) {
                   m_evalStack.get(m_evalStack.size() - 1) | StackSym::M);
 }
 
-Label* EmitterVisitor::getContinuationGotoLabel(StatementPtr s) {
-  Label* label = nullptr;
-  StatementListPtr stmts(static_pointer_cast<StatementList>(s));
-  for (int i = 0; i < stmts->getCount(); i++) {
-    StatementPtr s((*stmts)[i]);
-    if (s->is(Statement::KindOfFunctionStatement)) {
-      FunctionStatementPtr f(static_pointer_cast<FunctionStatement>(s));
-      always_assert(f->getFunctionScope()->isGenerator());
-      visit(f);
-    } else if (s->is(Statement::KindOfGotoStatement)) {
-      GotoStatementPtr g(static_pointer_cast<GotoStatement>(s));
-      always_assert(label == nullptr);
-      label = &m_gotoLabels[StringData::GetStaticString(g->label())];
-    } else {
-      not_implemented();
-    }
-  }
-  always_assert(label);
-  return label;
-}
-
-void EmitterVisitor::emitContinuationSwitch(Emitter& e,
-                                            SwitchStatementPtr sw) {
-  StatementListPtr cases(sw->getCases());
-  assert(cases);
-  const int ncase = cases->getCount();
-
+void EmitterVisitor::emitContinuationSwitch(Emitter& e, int ncase) {
   // There's an implicit fall-through "label 0" case in the switch
   // statement generated by the parser, so ncase is equal to the
   // number of yields in the body of the php function, which is one
   // less than the number of __yield__ labels.
+  if (ncase == 0) {
+    // fall-through to the label 0
+    e.UnpackCont();
+    e.PopC();
+    return;
+  }
+
+  // make sure the labels are available
+  m_yieldLabels.resize(ncase + 1);
+
   if (ncase == 1) {
     // Don't bother with the jump table when there are only two targets
-    CaseStatementPtr c1(static_pointer_cast<CaseStatement>((*cases)[0]));
-    visit(sw->getExp());
-    e.JmpNZ(*getContinuationGotoLabel(c1->getStatement()));
-  } else {
-    Label case0;
-    std::vector<Label*> targets(ncase + 1);
-    targets[0] = &case0;
-    for (int i = 0; i < ncase; ++i) {
-      CaseStatementPtr c(static_pointer_cast<CaseStatement>((*cases)[i]));
-      Variant v;
-      c->getCondition()->getScalarValue(v);
-      int caseIdx = v.asInt64Val();
-      assert(caseIdx > 0 && caseIdx <= ncase);
-      targets[caseIdx] = getContinuationGotoLabel(c->getStatement());
-    }
-    visit(sw->getExp());
-    e.Switch(targets, 0, 0);
-    case0.set(e);
+    e.UnpackCont();
+    e.JmpNZ(m_yieldLabels[1]);
+    return;
   }
+
+  std::vector<Label*> targets(ncase + 1);
+  for (int i = 0; i <= ncase; ++i) {
+    targets[i] = &m_yieldLabels[i];
+  }
+  e.UnpackCont();
+  e.Switch(targets, 0, 0);
+  m_yieldLabels[0].set(e);
 }
 
 DataType EmitterVisitor::analyzeSwitch(SwitchStatementPtr sw,
@@ -6697,6 +6666,7 @@ void EmitterVisitor::finishFunc(Emitter& e, FuncEmitter* fe) {
   copyOverExnHandlers(fe);
   copyOverFPIRegions(fe);
   m_gotoLabels.clear();
+  m_yieldLabels.clear();
   Offset past = e.getUnitEmitter().bcPos();
   fe->finish(past, false);
   e.getUnitEmitter().recordFunction(fe);

hphp/compiler/analysis/emitter.h

@@ -533,6 +533,7 @@ private:
   std::set<std::string,stdltistr> m_hoistables;
   LocationPtr m_tempLoc;
   std::map<StringData*, Label, string_data_lt> m_gotoLabels;
+  std::vector<Label> m_yieldLabels;
   MetaInfoBuilder m_metaInfo;
 public:
   Label& topBreakHandler() { return m_controlTargets.front().m_brkHand; }
@@ -584,8 +585,7 @@ public:
   void emitClsIfSPropBase(Emitter& e);
   Id emitVisitAndSetUnnamedL(Emitter& e, ExpressionPtr exp);
   void emitPushAndFreeUnnamedL(Emitter& e, Id tempLocal, Offset start);
-  Label* getContinuationGotoLabel(StatementPtr s);
-  void emitContinuationSwitch(Emitter& e, SwitchStatementPtr s);
+  void emitContinuationSwitch(Emitter& e, int ncase);
   DataType analyzeSwitch(SwitchStatementPtr s, SwitchState& state);
   void emitIntegerSwitch(Emitter& e, SwitchStatementPtr s,
                          std::vector<Label>& caseLabels, Label& done,

hphp/compiler/analysis/function_scope.cpp

@@ -65,7 +65,8 @@ FunctionScope::FunctionScope(AnalysisResultConstPtr ar, bool method,
       m_directInvoke(false),
       m_closureGenerator(false), m_noLSB(false), m_nextLSB(false),
       m_hasTry(false), m_hasGoto(false), m_localRedeclaring(false),
-      m_redeclaring(-1), m_inlineIndex(0), m_optFunction(0), m_nextID(0) {
+      m_redeclaring(-1), m_inlineIndex(0), m_optFunction(0), m_nextID(0),
+      m_yieldLabelCount(0) {
   init(ar);
   for (unsigned i = 0; i < attrs.size(); ++i) {
     if (m_userAttributes.find(attrs[i]->getName()) != m_userAttributes.end()) {
@@ -106,7 +107,7 @@ FunctionScope::FunctionScope(FunctionScopePtr orig,
       m_hasGoto(orig->m_hasGoto), m_localRedeclaring(orig->m_localRedeclaring),
       m_redeclaring(orig->m_redeclaring),
       m_inlineIndex(orig->m_inlineIndex), m_optFunction(orig->m_optFunction),
-      m_nextID(0) {
+      m_nextID(0), m_yieldLabelCount(orig->m_yieldLabelCount) {
   init(ar);
   m_originalName = originalName;
   setParamCounts(ar, m_minParam, m_maxParam);

hphp/compiler/analysis/function_scope.h

@@ -113,6 +113,8 @@ public:
   bool isClosure() const;
   bool isGenerator() const;
   bool isGeneratorFromClosure() const;
+  int allocYieldLabel() { return ++m_yieldLabelCount; }
+  int getYieldLabelCount() const { return m_yieldLabelCount; }
   bool hasGeneratorAsBody() const;
   MethodStatementRawPtr getOrigGenStmt() const;
   FunctionScopeRawPtr getOrigGenFS() const;
@@ -485,6 +487,7 @@ private:
   ExpressionListPtr m_closureValues;
   ReadWriteMutex m_inlineMutex;
   unsigned m_nextID; // used when cloning generators for traits
+  int m_yieldLabelCount; // number of allocated yield labels
   std::list<FunctionScopeRawPtr> m_clonedTraitOuterScope;
 };
 

hphp/compiler/expression/yield_expression.cpp

@@ -24,9 +24,9 @@ using namespace HPHP;
 
 YieldExpression::YieldExpression
 (EXPRESSION_CONSTRUCTOR_PARAMETERS,
- ExpressionPtr exp, int label)
+ ExpressionPtr exp)
   : Expression(EXPRESSION_CONSTRUCTOR_PARAMETER_VALUES(YieldExpression)),
-    m_exp(exp), m_label(label) {
+    m_exp(exp), m_label(-1) {
 }
 
 ExpressionPtr YieldExpression::clone() {
@@ -47,6 +47,9 @@ ExpressionPtr YieldExpression::clone() {
 void YieldExpression::analyzeProgram(AnalysisResultPtr ar) {
   assert(getFunctionScope() && getFunctionScope()->isGenerator());
   m_exp->analyzeProgram(ar);
+  if (m_label == -1) {
+    setLabel(getFunctionScope()->allocYieldLabel());
+  }
 }
 
 ConstructPtr YieldExpression::getNthKid(int n) const {

hphp/compiler/expression/yield_expression.h

@@ -27,12 +27,13 @@ DECLARE_BOOST_TYPES(YieldExpression);
 class YieldExpression : public Expression {
 public:
   YieldExpression(EXPRESSION_CONSTRUCTOR_PARAMETERS,
-                  ExpressionPtr exp, int label);
+                  ExpressionPtr exp);
 
   DECLARE_EXPRESSION_VIRTUAL_FUNCTIONS;
 
   ExpressionPtr getExpression() { return m_exp; }
-  int getLabel() { return m_label; }
+  int getLabel() { assert(m_label >= 0); return m_label; }
+  void setLabel(int label) { assert(m_label == -1); m_label = label; }
 
 private:
   ExpressionPtr m_exp;

hphp/compiler/parser/parser.cpp

@@ -109,8 +109,7 @@
 
 using namespace HPHP::Compiler;
 
-extern void prepare_generator(Parser *_p, Token &stmt, Token &params,
-                              int count);
+extern void prepare_generator(Parser *_p, Token &stmt, Token &params);
 extern void create_generator(Parser *_p, Token &out, Token &params,
                              Token &name, const std::string &closureName,
                              const char *clsname, Token *modifiers,
@@ -828,7 +827,7 @@ void Parser::onFunction(Token &out, Token *modifiers, Token &ret, Token &ref,
       ContinuationFromClosure : Continuation;
     const string &closureName = getAnonFuncName(fKind);
     Token new_params;
-    prepare_generator(this, stmt, new_params, funcContext.numYields);
+    prepare_generator(this, stmt, new_params);
 
     func = NEW_STMT(FunctionStatement, exp, ref->num(), closureName,
                     dynamic_pointer_cast<ExpressionList>(new_params->exp),
@@ -1130,7 +1129,7 @@ void Parser::onMethod(Token &out, Token &modifiers, Token &ret, Token &ref,
   if (funcContext.isGenerator) {
     const string &closureName = getAnonFuncName(ParserBase::Continuation);
     Token new_params;
-    prepare_generator(this, stmt, new_params, funcContext.numYields);
+    prepare_generator(this, stmt, new_params);
     ModifierExpressionPtr exp2 = Construct::Clone(exp);
     mth = NEW_STMT(MethodStatement, exp2, ref->num(), closureName,
                    dynamic_pointer_cast<ExpressionList>(new_params->exp),
@@ -1409,9 +1408,7 @@ void Parser::onYield(Token &out, Token &expr) {
     return;
   }
 
-  FunctionContext &funcContext = m_funcContexts.back();
-  int label = ++funcContext.numYields;
-  out->exp = NEW_EXP(YieldExpression, expr->exp, label);
+  out->exp = NEW_EXP(YieldExpression, expr->exp);
 }
 
 void Parser::onYieldBreak(Token &out) {

hphp/compiler/parser/parser.h

@@ -249,7 +249,6 @@ private:
     FunctionContext()
       : isNotGenerator(false)
       , isGenerator(false)
-      , numYields(0)
     {}
 
     // mark this function as generator; returns true on success
@@ -270,7 +269,6 @@ private:
 
     bool isNotGenerator;  // function determined to not be a generator
     bool isGenerator;     // function determined to be a generator
-    int numYields;        // number of plain yield statements seen so far
  };
 
   AnalysisResultPtr m_ar;

hphp/idl/continuation.idl.php

@@ -77,21 +77,6 @@ DefineFunction(
     'taint_observer' => false,
   ));
 
-DefineFunction(
-  array(
-    'name'   => 'hphp_unpack_continuation',
-    'return' => array(
-      'type'   => null,
-    ),
-    'args'   => array(
-      array(
-        'name'   => 'continuation',
-        'type'   => Object,
-      ),
-    ),
-    'taint_observer' => false,
-  ));
-
 ///////////////////////////////////////////////////////////////////////////////
 // Classes
 //

hphp/runtime/ext/ext_continuation.cpp

@@ -40,10 +40,6 @@ p_Continuation f_hphp_create_continuation(CStrRef clsname,
   return NULL;
 }
 
-void f_hphp_unpack_continuation(CObjRef continuation) {
-  throw_fatal("Invalid call hphp_unpack_continuation");
-}
-
 ///////////////////////////////////////////////////////////////////////////////
 
 static StaticString s___cont__("__cont__");

hphp/runtime/ext/ext_continuation.ext_hhvm.cpp

@@ -95,56 +95,6 @@ TypedValue* fg_hphp_create_continuation(HPHP::VM::ActRec *ar) {
 
 
 
-/*
-void HPHP::f_hphp_unpack_continuation(HPHP::Object const&)
-_ZN4HPHP26f_hphp_unpack_continuationERKNS_6ObjectE
-
-continuation => rdi
-*/
-
-void fh_hphp_unpack_continuation(Value* continuation) asm("_ZN4HPHP26f_hphp_unpack_continuationERKNS_6ObjectE");
-
-TypedValue * fg1_hphp_unpack_continuation(TypedValue* rv, HPHP::VM::ActRec* ar, int64_t count) __attribute__((noinline,cold));
-TypedValue * fg1_hphp_unpack_continuation(TypedValue* rv, HPHP::VM::ActRec* ar, int64_t count) {
-  TypedValue* args UNUSED = ((TypedValue*)ar) - 1;
-  rv->m_data.num = 0LL;
-  rv->m_type = KindOfNull;
-  tvCastToObjectInPlace(args-0);
-  fh_hphp_unpack_continuation((Value*)(args-0));
-  return rv;
-}
-
-TypedValue* fg_hphp_unpack_continuation(HPHP::VM::ActRec *ar) {
-    TypedValue rv;
-    int64_t count = ar->numArgs();
-    TypedValue* args UNUSED = ((TypedValue*)ar) - 1;
-    if (count == 1LL) {
-      if ((args-0)->m_type == KindOfObject) {
-        rv.m_data.num = 0LL;
-        rv.m_type = KindOfNull;
-        fh_hphp_unpack_continuation((Value*)(args-0));
-        frame_free_locals_no_this_inl(ar, 1);
-        memcpy(&ar->m_r, &rv, sizeof(TypedValue));
-        return &ar->m_r;
-      } else {
-        fg1_hphp_unpack_continuation(&rv, ar, count);
-        frame_free_locals_no_this_inl(ar, 1);
-        memcpy(&ar->m_r, &rv, sizeof(TypedValue));
-        return &ar->m_r;
-      }
-    } else {
-      throw_wrong_arguments_nr("hphp_unpack_continuation", count, 1, 1, 1);
-    }
-    rv.m_data.num = 0LL;
-    rv.m_type = KindOfNull;
-    frame_free_locals_no_this_inl(ar, 1);
-    memcpy(&ar->m_r, &rv, sizeof(TypedValue));
-    return &ar->m_r;
-  return &ar->m_r;
-}
-
-
-
 HPHP::VM::Instance* new_Continuation_Instance(HPHP::VM::Class* cls) {
   size_t nProps = cls->numDeclProperties();
   size_t builtinPropSize = sizeof(c_Continuation) - sizeof(ObjectData);

hphp/runtime/ext/ext_continuation.ext_hhvm.h

@@ -30,15 +30,6 @@ args => r8
 
 Value* fh_hphp_create_continuation(Value* _rv, Value* clsname, Value* funcname, Value* origFuncName, Value* args) asm("_ZN4HPHP26f_hphp_create_continuationERKNS_6StringES2_S2_RKNS_5ArrayE");
 
-/*
-void HPHP::f_hphp_unpack_continuation(HPHP::Object const&)
-_ZN4HPHP26f_hphp_unpack_continuationERKNS_6ObjectE
-
-continuation => rdi
-*/
-
-void fh_hphp_unpack_continuation(Value* continuation) asm("_ZN4HPHP26f_hphp_unpack_continuationERKNS_6ObjectE");
-
 
 } // !HPHP
 

hphp/runtime/ext/ext_continuation.h

@@ -28,7 +28,6 @@ namespace HPHP {
 FORWARD_DECLARE_CLASS_BUILTIN(Continuation);
 FORWARD_DECLARE_CLASS_BUILTIN(ContinuationWaitHandle);
 p_Continuation f_hphp_create_continuation(CStrRef clsname, CStrRef funcname, CStrRef origFuncName, CArrRef args = null_array);
-void f_hphp_unpack_continuation(CObjRef continuation);
 
 ///////////////////////////////////////////////////////////////////////////////
 // class Continuation

hphp/runtime/ext_hhvm/ext_hhvm_infotabs.cpp

@@ -191,7 +191,6 @@ TypedValue* fg_get_object_vars(VM::ActRec *ar);
 TypedValue* fg_call_user_method_array(VM::ActRec *ar);
 TypedValue* fg_call_user_method(VM::ActRec *ar);
 TypedValue* fg_hphp_create_continuation(VM::ActRec *ar);
-TypedValue* fg_hphp_unpack_continuation(VM::ActRec *ar);
 TypedValue* fg_ctype_alnum(VM::ActRec *ar);
 TypedValue* fg_ctype_alpha(VM::ActRec *ar);
 TypedValue* fg_ctype_cntrl(VM::ActRec *ar);
@@ -3020,7 +3019,7 @@ TypedValue* tg_9XMLWriter_endDTD(VM::ActRec *ar);
 TypedValue* tg_9XMLWriter_flush(VM::ActRec *ar);
 TypedValue* tg_9XMLWriter_outputMemory(VM::ActRec *ar);
 
-const long long hhbc_ext_funcs_count = 2208;
+const long long hhbc_ext_funcs_count = 2207;
 const HhbcExtFuncInfo hhbc_ext_funcs[] = {
   { "apache_note", fg_apache_note, (void *)&fh_apache_note },
   { "apache_request_headers", fg_apache_request_headers, (void *)&fh_apache_request_headers },
@@ -3190,7 +3189,6 @@ const HhbcExtFuncInfo hhbc_ext_funcs[] = {
   { "call_user_method_array", fg_call_user_method_array, (void *)&fh_call_user_method_array },
   { "call_user_method", fg_call_user_method, (void *)&fh_call_user_method },
   { "hphp_create_continuation", fg_hphp_create_continuation, (void *)&fh_hphp_create_continuation },
-  { "hphp_unpack_continuation", fg_hphp_unpack_continuation, (void *)&fh_hphp_unpack_continuation },
   { "ctype_alnum", fg_ctype_alnum, (void *)&fh_ctype_alnum },
   { "ctype_alpha", fg_ctype_alpha, (void *)&fh_ctype_alpha },
   { "ctype_cntrl", fg_ctype_cntrl, (void *)&fh_ctype_cntrl },

hphp/runtime/vm/translator/translator.cpp

@@ -2913,10 +2913,7 @@ void Translator::relaxDeps(Tracelet& tclet, TraceletContext& tctxt) {
 static bool checkTaintFuncs(StringData* name) {
   static const StringData* s_extract =
     StringData::GetStaticString("extract");
-  static const StringData* s_hphp_unpack_continuation =
-    StringData::GetStaticString("hphp_unpack_continuation");
-  return name->isame(s_extract) ||
-            name->isame(s_hphp_unpack_continuation);
+  return name->isame(s_extract);
 }
 
 /*

hphp/system/class_map.cpp

@@ -7146,12 +7146,6 @@ const char *g_class_map[] = {
   NULL,
   NULL,
   NULL,
-  (const char *)0x10006040, "hphp_unpack_continuation", "", (const char*)0, (const char*)0,
-  "/**\n * ( excerpt from\n * http://php.net/manual/en/function.hphp-unpack-continuation.php )\n *\n *\n * @continuation\n *             object\n */",
-  (const char *)-1, (const char *)0x2000, "continuation", "", (const char *)0x40, "", "", NULL,
-  NULL,
-  NULL,
-  NULL,
   (const char *)0x10006040, "assert_options", "", (const char*)0, (const char*)0,
   "/**\n * ( excerpt from http://php.net/manual/en/function.assert-options.php )\n *\n * Set the various assert() control options or just query their current\n * settings.\n *\n * @what       int     Assert Options Option INI Setting Default value\n *                     Description ASSERT_ACTIVE assert.active 1 enable\n *                     assert() evaluation ASSERT_WARNING assert.warning 1\n *                     issue a PHP warning for each failed assertion\n *                     ASSERT_BAIL assert.bail 0 terminate execution on\n *                     failed assertions ASSERT_QUIET_EVAL\n *                     assert.quiet_eval 0 disable error_reporting during\n *                     assertion expression evaluation ASSERT_CALLBACK\n *                     assert.callback (NULL) Callback to call on failed\n *                     assertions\n * @value      mixed   An optional new value for the option.\n *\n * @return     mixed   Returns the original setting of any option or FALSE\n *                     on errors.\n */",
   (const char *)0xffffffff, (const char *)0x2000, "what", "", (const char *)0xa, "", "", NULL,

hphp/system/continuation.inc

@@ -2,7 +2,6 @@
 
 #if EXT_TYPE == 0
 "hphp_create_continuation", S(999), "Continuation", S(0), "clsname", T(String), NULL, S(0), NULL, S(0), "funcname", T(String), NULL, S(0), NULL, S(0), "origFuncName", T(String), NULL, S(0), NULL, S(0), "args", T(Array), "N;", S(2), "null", S(0), NULL, S(16384), "/**\n * ( excerpt from\n * http://php.net/manual/en/function.hphp-create-continuation.php )\n *\n *\n * @clsname    string\n * @funcname   string\n * @origFuncName\n *             string\n * @args       map\n *\n * @return     Continuation\n *\n */", 
-"hphp_unpack_continuation", T(Void), S(0), "continuation", T(Object), NULL, S(0), NULL, S(0), NULL, S(16384), "/**\n * ( excerpt from\n * http://php.net/manual/en/function.hphp-unpack-continuation.php )\n *\n *\n * @continuation\n *             object\n */", 
 
 #elif EXT_TYPE == 1
 

hphp/test/test_parser_stmt.cpp

@@ -658,8 +658,7 @@ bool TestParserStmt::TestYieldStatement() {
 
   V("<?php function foo() { yield break;}",
     "function ($" CONTINUATION_OBJECT_NAME ") {\n"
-    "switch (hphp_unpack_continuation($" CONTINUATION_OBJECT_NAME ")) {\n"
-    "}\n"
+    "hphp_unpack_continuation();\n"
     "return;\n"
     "}\n"
     "function foo() {\n"
@@ -669,10 +668,7 @@ bool TestParserStmt::TestYieldStatement() {
 
   V("<?php function foo() { yield 123;}",
     "function ($" CONTINUATION_OBJECT_NAME ") {\n"
-    "switch (hphp_unpack_continuation($" CONTINUATION_OBJECT_NAME ")) {\n"
-    "case 1:\n"
-    "goto " YIELD_LABEL_PREFIX "1;\n"
-    "}\n"
+    "hphp_unpack_continuation();\n"
     "yield 123;\n"
     "}\n"
     "function foo() {\n"
@@ -687,13 +683,7 @@ bool TestParserStmt::TestYieldStatement() {
     "(__CLASS__, '3990978909_1', __METHOD__);\n"
     "}\n"
     "public function ($" CONTINUATION_OBJECT_NAME ") {\n"
-    "switch (hphp_unpack_continuation($" CONTINUATION_OBJECT_NAME ")) {\n"
-    "case 2:\n"
-    "goto " YIELD_LABEL_PREFIX "2;\n"
-    "\n"
-    "case 1:\n"
-    "goto " YIELD_LABEL_PREFIX "1;\n"
-    "}\n"
+    "hphp_unpack_continuation();\n"
     "yield 123;\n"
     "yield 456;\n"
     "}\n"

hphp/util/parser/hphp.y

@@ -143,56 +143,21 @@ static void on_constant(Parser *_p, Token &out, Token *stmts,
 ///////////////////////////////////////////////////////////////////////////////
 // continuation transformations
 
-void prepare_generator(Parser *_p, Token &stmt, Token &params, int count) {
+void prepare_generator(Parser *_p, Token &stmt, Token &params) {
   // 1. add prologue and epilogue to original body and store it back to "stmt"
   {
-    Token scall;
-    Token switchExp;
-    {
-      // hphp_unpack_continuation(v___cont__)
-      Token name;    name.setText(CONTINUATION_OBJECT_NAME);
-      Token var;     _p->onSynthesizedVariable(var, name);
-      Token param1;  _p->onCallParam(param1, NULL, var, false);
+    // hphp_unpack_continuation()
+    Token empty;
+    Token cname;   cname.setText("hphp_unpack_continuation");
+    Token unpack;  _p->onCall(unpack, false, cname, empty, NULL, true);
+    Token sunpack; _p->onExpStatement(sunpack, unpack);
 
-      Token cname;   cname.setText("hphp_unpack_continuation");
-      Token call;    _p->onCall(call, false, cname, param1, NULL, true);
+    Token stmts0;  _p->onStatementListStart(stmts0);
+    Token stmts1;  _p->addStatement(stmts1, stmts0, sunpack);
+    Token stmts2;  _p->addStatement(stmts2, stmts1, stmt);
 
-      switchExp = call;
-    }
-    Token sswitch;
-    {
-      _p->pushLabelScope();
-      {
-        Token cases;
-        for (int i = count; i > 0; i--) {
-          std::string si = boost::lexical_cast<std::string>(i);
-
-          Token label;   label.setText(YIELD_LABEL_PREFIX + si);
-          Token sgoto;   _p->onGoto(sgoto, label, false);
-                         _p->addGoto(label.text(), _p->getLocation(), &sgoto);
-
-          Token stmts0;  _p->onStatementListStart(stmts0);
-          Token stmts1;  _p->addStatement(stmts1, stmts0, sgoto);
-          Token stmts;   _p->finishStatement(stmts, stmts1); stmts = 1;
-
-          Token snum;    snum.setText(si);
-          Token num;     _p->onScalar(num, T_LNUMBER, snum);
-          Token scase;   _p->onCase(scase, cases, &num, stmts);
-          cases = scase;
-        }
-        _p->onSwitch(sswitch, switchExp, cases);
-      }
-      _p->popLabelScope();
-    }
-    {
-      Token stmts0;  _p->onStatementListStart(stmts0);
-      Token stmts1;  _p->addStatement(stmts1, stmts0, scall);
-      Token stmts2;  _p->addStatement(stmts2, stmts1, sswitch);
-      Token stmts3;  _p->addStatement(stmts3, stmts2, stmt);
-
-      stmt.reset();
-      _p->finishStatement(stmt, stmts3); stmt = 1;
-    }
+    stmt.reset();
+    _p->finishStatement(stmt, stmts2); stmt = 1;
   }
 
   // 2. prepare a single continuation parameter list and store it in "params"

hphp/util/parser/parser.cpp

@@ -247,10 +247,6 @@ void ParserBase::popLabelInfo() {
 
   for (unsigned int i = 0; i < info.gotos.size(); i++) {
     const GotoInfo &gotoInfo = info.gotos[i];
-    if (gotoInfo.label.find(YIELD_LABEL_PREFIX) == 0) {
-      labels.erase(gotoInfo.label);
-      continue;
-    }
     LabelMap::const_iterator iter = info.labels.find(gotoInfo.label);
     if (iter == info.labels.end()) {
       invalidateGoto(gotoInfo.stmt, UndefLabel);

hphp/util/parser/parser.h

@@ -40,7 +40,6 @@
 // NOTE: system/classes/closure.php may have reference to these strings:
 #define CONTINUATION_OBJECT_NAME       "__cont__"
 #define TYPED_CONTINUATION_OBJECT_NAME "__typedCont__"
-#define YIELD_LABEL_PREFIX             "__yield__"
 #define FOREACH_VAR_PREFIX             "__foreach__"
 #define NAMESPACE_SEP                  '\\'